Arsenal fans were sceptical, but as with Anelka, the transfer turned out better for the club than the players.

Petit in particular struggled at Barcelona, lasting only one season. In his 2008 autobiography, Petit revealed how he was shunned by his new teammates, and that the Barça coach didn't even know what position he played in.

Ashley Cole to Chelsea, 2006

Mike Hewitt/Getty ImagesAshley Cole

Trophies Won with New Club: 8 to date

Player Grade: A+

Arsenal Grade: C

At the time, it seemed like a decent bit of business for Arsenal. Cole certainly had to go after the bitter salary negotiations and flagrant Chelsea courtship detailed in his notorious book My Defence, and Arsenal were able to secure £5 million plus William Gallas in return.

But despite a promising start, it wasn't long before Gallas showed his age and temperament, which meant a £20-million valuation was completely off base.

Meanwhile at Chelsea, Cole quickly established himself as one of the club's most dependable and valuable players, helping the team to multiple trophies including the 2012 Champions League.

Cole's incongruous professionalism on the pitch and continued world-class skill at left-back have even partly rehabilitated his tarnished public image.

Thierry Henry to Barcelona, 2007

On paper, a win-win transfer. Thierry Henry finally won the Champions League with Barcelona, while Arsenal offloaded an expensive player on the wane.

And far from devastating the team, Henry's departure actually seemed to inspire the Arsenal squad, who by some accounts had been negatively overawed by their captain's stature.

But despite the trophies, Henry's increasingly rare performances at Barcelona made it clear his glory days at the highest level were over. In 2010 he was encouraged to transfer to the MLS, where he has created an impressive late-career rally at New York Red Bulls.

Henry's post-Barcelona form saw him make a sensational return on loan to Arsenal in the 2011/12 season.

But in what has become a trademark pattern, his early enthusiasm soon faded and mid-way through his second season at City, Adebayor found himself surplus to requirements.

Unfortunately for the striker, he was sent away on loan just before City started winning things.

Arsenal fans may rue the loss of a proven goal-scorer, but in retrospect the £25-million fee was more than generous for a player whose inconsistent form, salary demands and destabilizing dressing room influence have since made him seemingly impossible for City to unload.

Cesc Fabregas to Barcelona, 2011

Losing Fabregas was always going to be painful, but hardly unexpected. Arsenal knew it was only a matter of time before the Barcelona youth product returned home.

Unfortunately, so did everyone else, which hampered the club's ability to negotiate.

After damagingly protracted negotiations which dragged into the start of the Premier League season, Barcelona finally got their man for a reported £35 million. A month later, The Independent reported that Barcelona vice-president Josep Bartomeu acknowledged to Catalan paper Sport that Cesc was actually worth Arsenal's initial valuation of over £50 million.

Arsenal's failure to deal effectively with a transfer everyone knew was on the horizon not only cost them £15 million, but contributed to their worst Premier League start in years.

As for Cesc, joining Pep Guardiola's Barcelona was essentially guaranteed to end his trophy drought, and it delivered almost immediately with the 2011 UEFA Supercup win.

Yet it has not necessarily been an unblemished dream move. Champions League success continued to elude him. And Cesc's arrival coincided with Barcelona's first losing La Liga campaign in four years, a fact some observers have suggested is more than coincidence.